The Importance of Trichoscopy in Hair Diseases

Transcription

1 Chapter 04 The Importance of Trichoscopy in Hair Diseases Nida Kaçar* and Merve Akbay Department of Dermatology, Faculty of Medicine, Pamukkale University, Turkey * Corresponding Author: Nida Kaçar, Pamukkale Universitesi Tip Fak. Hastanesi, Dermatoloji Anabilim Dalı, E-409, Denizli, Turkey, Tel: ; n_gelincik@yahoo.com First Published April 23, 2018 Copyright: 2018 Nida Kaçar and Merve Akbay. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source. 2

2 Abstract Trichoscopy is the dermoscopic examination of hair, scalp, eyebrows and eyelashes gaining popularity day by day. It is a very helpful method that may decrease the necessity for histopathological examination. In this chapter, the trichoscopic findings of various hair and scalp diseases including hair shaft abnormalities, alopecias, and scalp abnormalities are discussed in detail. Introduction Trichoscopy is the examination of hair, scalp, eyebrows and eyelashes with either dermoscopy or videodermoscopy. Videodermoscopes enables documentation and measurements by achieving up to 160-fold magnification, or more in advanced systems. Hand-held dermoscopes provide 10-fold magnification; allows fast and cheap evaluation. Although being used since early 1990s, trichoscopy has gained popularity in early 2000s. It has become a widely used method in the diagnosis and follow-up of hair diseases including hair shaft abnormalities, both cicatrial and non-cicatricial alopecias, and scalp abnormalities [1]. Herein first the trichoscopic findings of normal hair are mentioned. Then the hair disorders with defined trichoscopic findings are discussed [Table 1]. 3

3 Table 1: Summarized trichoscopic findings. Trichoscopic findings Description Most Common Clinical Associations Schematic drawings Normal hairs Uniformly shaped and colored hairs Normal Vellus hairs Thin, bluntly ended, hypopigmented, wavy shaped hairs in weak appearance %10 of normal hair, increased in pattern hair loss Short regrowing hairs Regularly bended ribbon sign Short, sharp ended hairs gradually thinning from their proximal to distal end at upright position Normal Can be seen in regrowth phase of telogen effluvium Unusual hair shafts with beaded appearance, bended Specific for Monilethrix regularly at multiple locations with tendency to curve in different directions Trichorrhexis nodosa Trichotiodystrophy A hair shaft with a restricted area where the shaft splits longitudinally into numerous small fibers. The outer fibers bulge out, causing a segmental increase in hair diameter Tiger-tail appearance with polarized transilluminating dermoscopy Although can be seen in various acquired and inherited diseases, commonly result from trauma either mechanical or chemical Inherited hair shaft abnormality Trichorrhexis invaginata (bamboo hairs) Multiple small nodules spaced along the shaft at irregular intervals at low magnification, ball-in-cup appearance at high magnification Specific for Netherton syndrome Golf tee hairs Concave distal ended hairs Specific for Netherton syndrome Pili torti Flattened and twisted hairs on their own axis at irregular intervals Associated with various hair diseases Pili annulati Hair shafts with regular light bands that constitute more than a half of hair shaft width and usually shorter than the spacings between them Inherited hair shaft abnormality Crawling snake appearance Hair shafts with short wave cycles Specific for Wooly hairs Peripilar sign Brown spots surrounding hair ostiums Patterned hair loss Yellow dots Exclamation mark hairs Yellow to yellow-pink, round or polycyclic dots Sensitive finding for alopecia areata, also in various sizes seen in advanced patterned hair loss Short hairs tapering proximally and widening distally Alopecia areata and some other diseases in a less extent Tapered hairs (Coudability hairs) Long exclamation mark hairs not getting out of the field of view of a dermoscope Alopecia areata and some other diseases in a less extent intoxication Black dots Residues of pigmented hairs Alopecia areata, trichotillomania Broken hairs Regrowing pig tail hair Short hairs with hair shafts that appear normal except for irregular, ragged, distal ends Short, regularly coiled hairs with tapered ends Trichotillomania, traction alopecia, alopecia areata, tinea capitis Alopecia areata Zigzag hairs Hairs, bent at sharp angles, form zigzag structures Tinea capitis, alopecia areata 4

4 Coiled hairs Frayed ended irregularly coiled hairs Trichotillomani Hook hairs (question mark hairs) Partially coiled hairs Trichotillomani Flame hairs V-sign Tulip hairs Semi-transparent, wavy and cone shaped hair residues resembling a fire flame Two or more hairs emerging from one follicular unit that broken at the same length Short hairs with darker, tulip flower shaped ends Trichotillomania Trichotillomania Trichotillomania Hair powder Sprinkled hair residue Trichotillomania Follicular keratotic plugs Brownish yellow dots Discoid lupus eythematosus Follicular red dots Erythematous polycyclic, concentric structures Discoid lupus eythematosus White patches White areas lacking follicular openings Discoid lupus eythematosus Arborizing vessels Treebranch-like with wider caliber than the loops Discoid lupus eythematosus Honeycomb pigmented network Pigment network in honeycomb pattern Discoid lupus eythematosus Hair casts (peripilar keratin casts) Firm, white, tubular masses encircling hair shafts Nonspecific Traction alopecia Comma hairs Short, comma shaped hairs, Tinea capitis Corkscrew hairs Morse Code-like hairs (Bar code-like hairs) Trichoptilosis Trichoschisis or trichoclasis Hairs with multiple twists and coils, forming corkscrew-like structures Hairs with multiple thin white bands across the hair shaft Longitudinal splitting of the distal end of hair shaft A clean transverse fracture across the hair shaft Tinea capitis Tinea capitis Non-spesific Trichothiodystrophy, secondary to conditions that weaken the hair shaft 5

5 Normal Hair A normal terminal hair is uniform in thickness and color throughout its length. Hair shafts may be different from each other in terms of color and thickness in an individual. Hair pigmentation differentiation in graying individuals is a normal finding. Normal hair thickness is generally more than 55 mm [2]. Thickest hairs are localized in frontal area. The ratio of thick hairs is more than 61%, 52% and 54% of total hair count in frontal, occipital and temporal areas, respectively; while thin hairs are less than 10% and 13% of total hairs in frontal/occipital areas and in temporal areas, respectively. Up to 2 short hairs in frontal and occipital area and 3 short hairs in temporal area on trichoscopic image in one field of vision at 20-fold magnification is within normal range. One or two yellow dots can be seen at 70- fold magnification. Pin-point like vessels and arborizing vessels are the two types of vessels that can be seen in healthy individuals. While pin-point like vessels are frequent in frontal area, arborizing vessels dominance is seen in the rest of scalp [3]. Dermoscopic examination with hand-held dermoscopes may allow estimating hair shaft thickness roughly as thin, normal and thick. However, hair shaft thickness can be measured in micrometers with some digital dermoscopy systems. Medulla of terminal hairs may be continuous, interrupted, fragmented or absent. Vellus hairs, which are less than 3 mm long and 30 mm thick, comprise up to 10% of normal hairs; and they must be distinguished from short regrowing hairs [2][Figure 1]. Although exclamation mark hairs, white dots, cadaverized hairs, and broken hairs are not expected in healthy individuals, it should be kept in mind that peripilar sign can be [3]. Dirty dots that present on the scalp as clumped and haphazardly arrayed particulate debris and loose fibers of various colors can be seen in prepubertal age; dirty dots can be best visualized 20 and 70-fold magnification [4]. Follicular red dots were proposed to be a normal trichoscopic finding in patients with pigmentary disorders including vitiligo and albinism [5]. 6

6 Figure 1: Regrowing hair (red arrow head) and vellus hairs (green arrow head) together in a case of alopecia areata. Figure 2: Regularly bended ribbon sign in a case of monilethrix. 7

7 Hair Shaft Abnormalities Monilethrix Regularly bended ribbon sign was reported to define unusual hair shafts with beaded appearance, bended regularly at multiple locations with tendency to curve in different directions [6] [Figure 2]. Trichorrhexis Nodosa Presents with characteristic thrust paint brushes appearance on microscopy. This appareance can be detected with trichoscopy [7,8]. Trichothiodystrophy Hair shafts present with typical bright and dark bands reassembling the tiger-tail under polarized microscope. Trichoscopy was found to be non-specific in trichothiodystrophy; but could be used to select the hairs requiring further analysis that showed a non-homogenous structure reassembling grains of sand within the hair shaft and a slightly wavy contour at higher magnification [9]. Two new methods called by the authors as polarized transilluminating dermoscopy have been very recently described. In the first method polarized light has been created by projecting a light-emitting diode from a cellular telephone through a polarizing dermatoscope, then the hair has been placed for transillumination and finally another polarizing dermoscope has been used to examine the hair. In the second method, polarizing light reflects off the mirror to transilluminate the specimen placed on the mirror [10]. Trichorrhexis Invaginata Also called bamboo hair is one of the three characteristic features of Netherton syndrome. Typical ball in cup appearance formed by invagination of the distal portion of the hair shaft into its proximal portion is seen under microscopy. Occasionally distal end fractures and only proximal half of the invaginate node can be seen which is 8

8 called golf tee like hairs. These findings can be easily detected with trichoscopy [2,9,11,12]. Pili Torti Trichoscopy is reported to be useful. Twists in hair shafts are seen [7,9]. Pili Annulati Hair shafts demonstrate regular light bands on trichoscopic examination. These bands constitute more than a half of hair shaft width. The boarders of bands are blurry and the spacing between these bands is usually longer than the length of the bands themselves [9]. Woolly Hair Hair shafts presents with short wave cycles giving the hair a crawling snake appearance [9]. Alopecias Several diseases result in cicatricial alopecia including discoid lupus erythematosus, lichen pilanopilaris, frontal fibrosing alopecia and so on. Some trichoscopic findings can be seen in all cicatricial alopecias leading the clinician to suspect a cicatricial disease. Loss of follicular openings, perifollicular scaling, white patches, perifollicular halo and large white dots with blunt borders are among them [Figure 3]. White dots are thought to represent scarred fibrous follicular tracts and can become confluent and result in the disappearance of the follicular openings. Loss of follicular openings can also be seen in long-standing non-cicatricial alopecias; so loss of follicular openings is more diagnostic for cicatricial alopecias when present in conjunction with white and milky-red areas [13-16]. Trichoscopic findings also yield to select the optimal biopsy site in cicatricial alopecias [17]. 9

9 Figure 3: Loss of follicular openings, white patches and white dots are seen in cicatricial alopecia. Non-Cicatricial Alopecias Telogen Effluvium Trichoscopy is not very meaningful in telogen effluvium. However, there are some clues to differentiate telogen effluvium from other hair disorders. Thickest hairs are placed in the frontal region whereas thinnest hairs in the occipital region similar to healthy controls. Thin hairs correspond to newly growing hairs that are short, sharp ended, and become gradually thinner from their proximal to distal end; this differs from the thin hairs corresponding to vellus hairs in patterned hair loss (PHL). Single hair pilosebase units mostly exist in the temporal regions [18]. Patterned Hair Loss PHL, also called androgenetic alopecia, is characterized by progressive hair thinning of the scalp localized to mainly the frontal and the crown regions [13]. Thin, intermediate and thick hairs are found altogether in the affected areas leading to more than 20% hair diam- 10

10 eter diversity as an early sign of the disease [19]. Hair diameter diversity can be detected better with trichoscopy than with the unaided eye [14] [Figure 4]. Both male and female PHL present with similar trichoscopic findings. The mean hair thickness has been found to be statistically lower in the frontal area than the occipital area in PHL. Thin hairs correspond to vellus hairs that are uniformly thin and with bluntly ends. Single hair pilosebase units mostly placed in the frontal region. Peripilar sign and yellow dots are more common than healthy controls [18,20]. Peripilar sign is a brown spot surrounding hair ostium of which diameter is less than 1 mm [21]. Recently, white version of peripilar sign has been defined. White peripilar sign has been related to perifollicular fibrosis in the late stage of disease.the other trichoscopic findings found to be associated with advanced PHL include scalp honeycomb pigmentation, pinpoint white dots and yellow dots [22]. Figure 4: Mean hair diameter diversity > %20 in effected scalp. Scalp honeycomb pigmentation is the composition of contiguous brown circles resembling pigment network of melanocytic lesions that attributed to chronic sun exposure. The extent of pigmentation 11

11 is determined by the amount of hair that can protect scalp from sun exposure [14]. Pinpoint white dots are evenly distributed white dots with a diameter of mm between the follicular ostia that correspond to the empty hair follicle ostia or to the epidermal portion of eccrine sweat ducts. Pinpoint white dots can be identified more clearly on the contrast of tanning scalp [23]. Yellow dots are seen as yellow to yellow-pink, round or polycyclic dots in various sizes that were thought to represent distended follicular infundibulum filled with keratinous material and sebum [14]. Therefore, it is not surprising to see abovementioned trichoscopic findings in advanced PHL. Alopecia Areata Typically present with sharply bordered, skin colored alopecic patches. Exclamation mark hairs, 1-3 cm long hairs tapering proximally and widening distally, within or at the periphery of the patches are characteristics of the disease. Exclamation mark hairs can be recognized with trichoscopy even when they are as short as 0,1 to 0,5 mm [24,25] [Figure 5]. Very elongated exclamation mark hairs are called as tapered hairs that taper from distal end to proximal end and of which distal end does not fit in the field of view of the dermoscope [24]. Coudability hairs were used historically for tapered hairs. They are thought to be partially strucked hairs [26]. Other trichoscopic findings include yellow dots, black dots containing cadaverized hair that are broken as a result of severe inflammatory process before emergence from scalp, broken hairs, vellus hairs, regrowing pigtail hairs (circular or oval), and less often trichorrhexis nodosa, monilethrix-like hairs, Pohle-Pinkus constrictions, upright regrowing hairs and zig-zag hairs [13,27]. Black dots, tapered hairs and broken hairs were detected as the most specific and; yellow dots and short vellus hairs as the most sensitive findings for the diagnosis of alopecia areata. Especially the combination of yellow dots and short vellus hairs was demonstrated to enhance the sensitivity of the diagnosis [28] [Figure 6].The lengths of broken hairs tend to be similar in a field of view [27]. It should be kept in mind that dissecting cellulitis of scalp is an important simulator of alopecia areata that can present 12

12 with black, yellow and/or red dots; but not with exclamation mark hairs [29,30]. In addition, black dots in alopecia areata tend to be uniform in size and shape [27]. Trichoscopic findings also give clues about the activity and severity of the disease. Exclamation mark hairs, tapering hairs, broken hairs, black dots and cadaverized hairs are associated with active and progressive disease; vellus hairs mean initial hair regrowth indicating good prognosis. Scalp skin appears smooth and thin with evident follicular openings when the disease converts to chronic form. In long-standing disease hair follicle openings obstruct by keratotic plugs [28,31]. Consistent trichoscopic findings during the disease course were observed in the lymph node cell-induced alopecia areata lesions of three C3H/HeJ mice [32]. Black dots and yellow dots are associated with more severe disease while short vellus hairs are associated with less severe disease [28]. The frequency of the trichoscopic findings may differ according to the type of the disease. Short vellus hairs is the most common finding in all types of alopecia areata except for ophiasis and universalis types, in which yellow dots are most common findings [28]. Recently, a new activity scoring system for alopecia areata was developed that involved trichoscopic findings was, called Alopecia Areata Progression Index. The trichoscopic findings taken into consideration in that scoring system included exclamation mark hairs, broken hairs, black dots and dystrophic vellus hairs (cadaverized hairs) [33]. Figure 5: Clinical view (A) and trichoscopic view (B) of exclamation mark hairs. 13

13 Figure 6: Yellow dots in conjunction with vellus hairs in alopecia areata. Trichotillomania Hair shaft abnormalities due to trauma can be detected with trichoscopy. Hair fractures result in black dots, broken hairs at different lengths, fraying (split) ended hairs, coiled hairs depending on the length of hair exposed to trauma. Hair shafts fracture due to pulling and the remaining hair part of the hair may coil. This produces coiled hairs, which are in irregular appearance with frayed ends. Areas with signs of scratching and bleeding may accompany [34]. Partially coiled hairs are also named as hook hairs or question mark hairs [27]. Yellow dots, one of the most sensitive findings for the diagnosis of alopecia areata, can also be seen in trichotillomania. Although it was suggested that yellow dots in trichotillomania contain black dots, differently from alopecia areata, further studies did not confirm this suggestion; however, when present, the number of yellow dots are very limited when compared to alopecia areata [27,28,34,35]. Another important difference from alopecia areata is that exclamation mark hairs are unexpected in trichotillomania; however, hairs with fraying ends may resemble exclamation mark hairs [34]. Later defined character- 14

14 istic trichoscopic findings for trichotillomania include flame hairs, v- sign, tulip hairs and hair powder. Flame hairs develop due to severe mechanical hair pulling and shredding and seen as semi-transparent, wavy and cone shaped hair residues resembling a fire flame. If hair shafts are damaged almost completely, only a sprinkled hair residue remains that was referred as hair powder. V-sign occurs when two or more hairs emerging from one follicular unit are pulled simultaneously and break at the same length above scalp surface. Tulip hairs are short hairs with darker, tulip flower shaped ends that develop when a hair shaft fractures diagonally [Figure 7]. While flame hairs and hair powder were detected in only trichotillomania, V-sign and tulip hairs were observed also in alopecia areata, but only in a small proportion. Just the opposite, exclamation mark hairs may also present in trichotillomania rarely [27]. Trichotillomania may coexist with alopecia areata which can cause diagnostic challenge [36]. Although rare, when present yellow dots are sparse, distributes irregularly and contains a black dot in their central part. Black dots can also be seen in a quarter of patients with trichotillomania, whereas their diameter and shape show high variability [27]. Follicular microhemorrhage is a red dot corresponding to follicular ostia capped or stuffed with blood clot, recently observed trichoscopic finding in four patients, which can be easily detectable by dry dermoscopy [37]. Figure 7: V-sign (red arrow head), tulip hairs (green arrow heads), flame hair (circle) and a a lot of black dots, broken hairs and hair powders in trichotillomania. 15

15 Loose Anagen Syndrome and Short Anagen Syndrome Trichoscopy was thought to be useless in these diseases until recently [38]. Rectangular black granular structures have been reported to be a unique trichoscopic feature of loose anagen syndrome, which differ from black dots in terms of their rectangular shape and granular structure. Follicular units with single hair have also been observed in 92.9% of hair units in loose anagen syndrome. Solitary yellow dots have also accompanied [39]. Temporal Triangular Alopecia Normal hairs are replaced by vellus hairs due to hair miniaturization in a localized area in triangular, oval or lancet shapes. It can be confused with several hair disorders including alopecia areata, traction alopecia, trichotillomani, aplasia cutis congenita and even patterned hair loss, especially when emerged in adulthood, localized in temporoparietal or occipital scalp and/or showed bilateral involvement [40]. Normal follicular openings with short vellus hairs in different lengths surrounded by normal terminal hairs can be elucidated with trichoscopy. White hairs are also seen. Diagnostic trichoscopic findings for other types of localized alopecia should be absent [40-44]. Cicatricial Alopecias There are various trichoscopic findings that can represent clues to specify the cicatricial alopecia. The presence of perifollicular erythema and/or scale in conjunction with loss of follicular openings is helpful for the diagnosis of frontal fibrosing alopecia [45,46]. Similar ticshoscopic findings are seen in classic lichen pilanopilaris [46,47] [Figure 8]. Follicular keratotic plugs, follicular red dots, white patches, arborizing vessels, honeycomb pigmented network, dyschromia, and variable scaling lead to the diagnosis of discoid lupus erythematosus [14,46,48-50]. Follicular red dots were observed to disappear with hair regrowth after the end of successful therapy [48]. Traction alopecia is suggested when hair casts around the hair shafts at the 16

16 periphery of the alopecic patch present in conjunction with loss of follicular openings and reduced hair density in a patient with patchy or marginal alopecia [51]. Dissecting cellulitis, especially of early lesions, may present with yellow and black dots, vellus hairs, broken hairs and even exclamation mark hairs simulating alopecia areata; but white dots in long-standing disease [52,53]. Interfollicular twisted red loops localized around actively affected follicles and white dots are the first reported trichoscopic findings for folliculitis decalvans. The trichoscopic hallmark is the presence of multiple hairs emerging from one single dilated follicular orifice. Dry trichoscopy should also be performed that perifollicular hyperkeratosis and crusts can be seen more clearly. Perifollicular erythema has also been observed in a recent study involving 82 patients [14,54-56]. Figure 8: Perifollicular erythema and/or scale in conjunction with loss of follicular openings in lichen planopilaris. Scalp Diseases Inflammatory Scalp Diseases Trichoscopy is also helpful in the diagnosis of inflammatory skin diseases effecting scalp. Red dots and globules representing the tortuous and dilated blood vessels within the elongated dermal papillae were reported to be the most significant trichoscopic features of scalp 17

17 psoriasis [Figure 9]. Twisted red loops and glomerular vessels were also seen in a considerable amount of scalp psoriasis cases that can help diagnosis. Compared to psoriasis, red dots and globules are not expected in seborrhoeic dermatitis, and characteristically arborizing vessels and atypical red vessels indicating markedly dilated capillaries in slightly hyperplastic rete ridges were commonly observed. Vascular structures can be observed better, particularly, after removing scales by the application of ultrasound gels [14,57]. Trichoscopy can also help to differentiate scalp involvement of systemic lupus erythematosus from alopecia areata and telogen effluvium. Scaling, telangiectasia, reduction in the number of hair fibres per follicular unit, hair shaft hypopigmentation, uneven hair shaft diameters, increases in short vellus hair numbers and focal atrichia are the reported trichoscopic clues, in the absence of the typical trichoscopic characteristics of alopecia areata, for the scalp involvement of systemic lupus erythematosus [58]. Extravasations, yellow hemorrhagic crusts, yellow dots with whitish halo (fried egg sign), white or yellow diffuse scaling, white polygonal structures and linear serpentine vessels are the reported trichoscopic clues suggesting pemphigus. Extravasations and white diffuse scaling are the most common trichoscopic findings in pemphigus vulgaris and pemphigus foliaceus, respectively [59]. While pemphigus vulgaris can be suggested when extravasations, yellow hemorrhagic crusts, dotted vessels with whitish halo, circular vessels, or polymorphic vessels are present; the combination of extravasations, yellow hemorrhagic crusts, yellow diffuse scaling, and tubular scaling should direct to pemphigus foliaceus [60]. Trichoscopic observations in few cases were reported for various skin diseases, as well. Two types hair was observed in three cases of lichen simplex chronicus; short hair shafts emerging as a single stem from a follicular opening spliting into two or three hairs of similar thickness proximally at the level of the surface and short hair shafts with the same appearance, but with also distal split of the hair tips into two or three tiny hair endings which are called broom hair fibers [61]. Yellowish to pale diffuse orange discoloration and orange round 18

18 spots with few dystrophic hairs were observed in two cases of scalp sarcoidosis [62]. Figure 9: Red dots and glomerular vessels in scalp psoriasis. Infectious Scalp Diseases Comma hairs that are homogeneous in thickness and pigmentation, with sharp curved ends is the first reported trichoscopic markers for tinea capitis [63]. Other findings include corkscrew and broken hairs [Figure 10]. Corkscrew hairs were firstly observed in black children and it was suspected that corkscrew hairs could be a variation of the comma hairs in black patient hair types or specific for Trichophyton soudanense infection [64]. Subsequent researches established that corckscrew hairs were also present in tinea capitis caused by other dermatophytes and also in also considerable amount of white patients with dark phenotype in addition to black patients [65-69]. More recent findings observed include zigzag and morse code-like hairs [70]. The hairs with multiple white bands across the 19

19 hair shaft giving the hair morse code appareance are called as morse code-like hairs ; bar-code like hairs are also used synonymously. It was suggested that those white bands to be less resistant and therefore the hair shafts bent from those bands composing zigzag hairs [71-73]. Morse-code hairs were argued to result from ectothrix-type hair infection [74]. Another infectious scalp disease that trichoscopy contribute to diagnosis is pediculosis capitis. Trichoscopy allows both differentiating nits from hair casts and scales and differentiating nits containing vital nymphs from empty nits [Figure 11]. So, response to treatment can be also evaluated by trichoscopic examination. Even alive lice can be detected, as well [75,76]. Figure 10: Trichoscopic findings in a case of tinea capitis; morse code-like hair (red arrow head), comma hairs (green arrow heads), broken hairs (asterix) and zigzag hair (circle). 20

20 Figure 11: Trichoscopic view of a nit containing vital nymph. Conclusions Trichoscopy became a standard procedure in the diagnosis of hair and scalp diseases. It is a rapid and non-invasive method that facilitates its use in routine clinical practice and reduces the need for more time-consuming or invasive methods. It should be kept in mind that the use of polarized or non-polarized dermoscopy modes may lead to differences in the visualization of trichoscopic findings [77]. Acknowledgement The authors would like to thank to Mustafa Özçelikörs for his precious contributions in the preparation of schematic drawings. References 21

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